1. Field of the Invention
This invention relates to radiation curable coatings, adhesives, inks, and molded articles. The invention also relates to clear, transparent molded articles useful as lenses, laminating resins, and novel unsaturated metal sulfates.
2. Description of the Prior Art
The use of metal (meth)acrylates such as zinc, calcium, and magnesium salts of acrylic or methacrylic acids as crosslinking monomers for use with elastomers to promote adhesion to substrates is well known. As described in Proudfit, U.S. Pat. No. 5,314,187, for example, zinc acrylate, zinc diacrylate, and zinc methacrylate are particularly suitable crosslinking agents for elastomers such as EPDM, 1,4-butadiene, isoprene, chloroprene, and the like. Ahmad et al., U.S. Pat. No. 5,506,308, teaches use of unsaturated carboxylic metal salts such as zinc diacrylate in curable elastomeric compositions wherein the elastomer may be a nitrile rubber, EPDM, EVA, and the like. Other prior patents which teach zinc acrylate, zinc diacrylate, zinc methacrylate, calcium diacrylate, and calcium dimethacrylate as crosslinking agents for elastomers include U.S. Pat. Nos. 5,731,371; 5,721,304; 5,656,703; 5,208,294; 5,126,501; 4,918,144; 4,770,422; 4,720,526; 4,715,607; 4,716,409; 4,529,770; 4,500,466; 4,495,326; 4,165,877; 4,065,537; and 4,264,075.
One disadvantage of such metal salts of carboxylic acids is their poor oil solubility. For example, they are relatively insoluble in organic monomers and oligomers.
Soluble zinc and calcium salts of ethylene glycol-methacrylate-phthalate (EMD) prepared in aqueous solution, and then copolymerized with methyl methacrylates (MMA), styrene (ST), and hydroxyethyl methacrylate (HEMA) were disclosed by Matsuda, et al., Preparation and Copolymerization of Divalent Metal Salts of Ethylene Glycol-Methacrylate-Phythalate, J. App. Poly. Sci., 17, 1941-1952 (1973), as ionic crosslinkers. The resultant crosslinked copolymers are shown to have improved physical properties.
U.S. Pat. No. 3,847,846 assigned to Kansai Paint Co., Ltd., teaches electrically conductive resins prepared from metal salts of certain sulphonates, phosphates, or phosphoric acid diesters, with an epoxide, optional solvent, polymerization initiator, and/or photosensitizer, and useful for magnetic tape and the like.
Matsuda, et al., U.S. Pat. No. 3,899,382, teaches polyvalent metal salts of compounds such as diethylene glycol methacrylate phthalate, mixed with an organic peroxide.
Matsuda, et al., Metal-Containing Cured Resins Based on Divalent Metal Salts of Ethylene Glycol-Methacrylate-Maleate, Poly Eng. and Sci., 18, No. 8, 628-633, June 1978, teach solubility of such salts in St., MMA, and EA, and copolymerization with such vinyl monomers to produce polymers having high heat distortion temperature, tensile strength, compressive strength, impact strength, and Rockwell hardness, as well as resistance to chemical attack.
Japanese Kokai 295285 of May 7, 1991, teaches use of magnesium, aluminum, or calcium salts of unsaturated phosphate compounds as additives for coatings to improve adhesion to metals.
Okamoto, et al., Effect of divalent metal salts of dibasic acid mono (methacryloyloxy propyl) esters on adhesive properties, Int. J. Adhesion and Adhesives, 9, No. 1, January 1989, teach peroxide cured adhesives prepared by copolymerizing such monomers with hydroxy propyl methacrylate (HPM).
The art of radiation curable coatings, adhesives, and inks is different from the art of peroxide curable polymers. In the radiation curable field, the current art uses only oil insoluble metal salts as adhesion promoters. No one has previously proposed oil soluble metal salts of carboxylic acids in the radiation curable art.
3. Objects
It is, therefore, an object of the present invention to provide improved radiation curable adhesives, coatings, and inks, transparent molded articles useful as lenses, and thermoset laminating resins.
It is another object to provide novel polymerizable, unsaturated metal sulfates which are oil soluble and useful in such compositions.
These objects, and others which will become apparent from the following disclosure, are provided by the invention which, in one aspect, includes a composition suitable for a radiation cured coating, adhesive, ink, or photoresist comprising (A) at least one polymerizable, ethylenically unsaturated compound of the formula 
wherein
M is one or more metal atoms of valence n, wherein n=yxc2x7w, and wherein M is optionally more than one metal atom, with the proviso that the global equivalent metal valence is n=wxc2x7y;
n is an integer of about 1-6;
R is a residue of a compound having anhydride and/or carboxylic acid groups with an initial equivalent carboxy equivalent functionality defined by the equation f=x+y+z, wherein f is an integer of about 2 to 30;
R1 is a residue of a hydroxy-containing ethylenically unsaturated compound;
R2 is H or a residue of a hydroxy containing ethylenically unsaturated compound different from R1;
R3 is a residue of a hydroxy-containing ethylenically unsaturated compound;
w is the number of moieties having residue R required for metal valence n;
x is an integer of about 1 to fxe2x88x921;
y is an integer of about 1 to 2 (the number of intramolecular carboxylates bonded to M);
z is an integer of about 0 to fxe2x88x922;
Y is H or R3; and
(B) at least one copolymerizable ethylenically unsaturated monomer or oligomer.
In another aspect, the invention includes a polymer, especially in the form of a coating, adhesive, ink, or molded article prepared by curing such a composition in the presence of a free radical initiator and/or radiation.
A further aspect of the invention is a solution of compound (A) in copolymerizable ethylenically unsaturated monomer or oligomer (B), alone or in an inert solvent. Such solutions can be prepared by forming compound (A) in the presence of the copolymerizable ethylenically unsaturated monomer or oligomer (B) and optionally in the presence of an inert solvent.
Still another aspect of the invention is a molded article polymerized from such a composition, the article having a refractive index useful for lenses.
A still further aspect is a process of preparing polymerizable, ethylenically unsaturated compounds (A) of formula (I), (II), (III) comprising reacting a hydroxy compound with a polyacid, anhydride, sulfur oxide, or phosphorus oxide compound to form an acid functional compound, and reacting the acid functional compound with a metal compound.
In another aspect, the invention includes a thermoset copolymer of a monomer mixture comprising (A) a compound according to formula (I), (II), or (III), and a (B) a polyfunctional (meth)acrylate or allylic compound.
Another aspect is a composition suitable for laminating resins having high heat distortion temperature, comprising an ethylenically unsaturated monomer, a free radical initiator, and a crosslinking monomer according to formula (I), (II), or (III).
The invention also comprises a compound of formula (III), i.e., a polymerizable, ethylenically unsaturated sulfate compound of the formula 
wherein
M=metal;
n=valence of M; and
R3=a residue of an unsaturated hydroxy compound; the compound being useful in making certain of the radiation curable compositions.
The oil soluble metal salts of formula (I), (II), or (III) useful in the radiation curable compositions of the invention can be prepared by any appropriate process. A preferred process comprises reacting a hydroxy compound with a carboxylic polyacid or anhydride, a sulfur oxide compound, or a phosphorus oxide compound to form an acid functional compound, and reacting that acid functional compound with a metal compound. The compounds of formula (I) are prepared, from carboxylic polyacids or anhydrides, whereas the compounds of formula (II) are prepared from phosphoric acids, and the compounds of formula (II) are prepared from sulfuric acids.
The hydroxy compounds used in such preparation can be saturated or unsaturated compounds. Saturated hydroxy compounds can be used to prepare compounds of formula (I) when the polyacid and/or anhydride compound contains ethylenic unsaturation which can be employed in the resultant compound for polymerization, especially with other polymerizable, ethylenically unsaturated compounds.
For the hydroxy compounds containing an ethylenically unsaturated group, the unsaturation can be provided by (meth)acrylic, allyl, propenyl, and/or vinyl groups. As used herein, the term xe2x80x9c(meth)acrylicxe2x80x9d is intended to include methacrylic, acrylic, and mixtures thereof.
Some examples of such suitable hydroxy compounds include hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, (C1 to C6) alkyl glycidyl (meth)acrylates, aryl glycidyl (meth)acrylates, allyl glycidyl (meth)acrylate, trimethylolpropane mono- and di-(meth)acrylate, pentaerythritol mono-, di-, and tri-(meth)acrylate, dipentaerythritol mono-, di-, tri-, tetra-, and penta-(meth)acrylate, glycerol mono- and di-(meth)acrylate, neopentyl glycol mono(meth)acrylate, hexanediol mono(meth)acrylate, tris(2-hydroxyethyl)isocyanurate mono- and di-(meth)acrylate, ethoxylated or propoxylated versions of all of the above, polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, polyethylene/propylene glycol mono(meth)acrylate, polybutylene glycol mono(meth)acrylate, polytetramethylene glycol mono(meth)acrylate, hydroxy polycaprolactone mono(meth)acrylate, and the like. Residues of these compounds are represented by R1 or R3 in formulas (I), (II), and (III).
Examples of hydroxy-allyl compounds include allyl alcohol, propoxylated or ethoxylated allyl alcohol, cinnamyl alcohol, crotyl alcohol, 3-butene-1-ol, 3-butene-2-ol, linalool, 2-cyclohexen-1-ol, 2-cyclopenten-1-ol, 2-butene-1,4-diol, glycerol mono- and di-allyl ethers, trimethylolpropane mono- and di-allyl ethers, and the like.
Hydroxy-propargyl compounds, for example, propargyl alcohol, propoxylated or ethoxylated propargyl alcohol, 2-butyn-1-ol, 3-butyn-1-ol, 3-butyn-2-ol, and the like are also suitable.
Other hydroxy compounds such as hydroxy-vinyl compounds, for example, ethylene glycol vinyl ether, propylene glycol vinyl ether, 1,4-butanediol vinyl ether, 1,3-butanediol vinyl ether, 1,6-hexanediol vinyl ether, 2-methyl-1,3-propane diol vinyl ether, di(ethylene glycol) vinyl ether, di(propylene glycol) vinyl ether, and the like can be used.
In the case of compounds of formula (I), polyacids or anhydrides which can be reacted with hydroxy compounds have either two or more carboxylic acid groups, or at least one anhydride group, or a combination thereof, such as one anhydride group and one carboxyl group. The hydroxy compound reacts with this compound to form a carboxyl functional compound which is suitable for reaction with a metal compound to form an oil soluble, polymerizable salt. The carboxy equivalent functionality of polycarboxylic acids and anhydrides is about 2-30. Preferably, the range is about 2-6.
For the compounds of formula (I), some suitable compounds containing anhydride and/or carboxyl groups which react with the hydroxyl compounds include phthalic anhydride, isophthalic acid, terephthalic acid, tetrabromophthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, itaconic anhydride, itaconic acid, phthalic acid, trimellitic anhydride (which contains one anhydride and one carboxyl group), pyromellitic anhydride, 5-norbornene-endo-2,3-dicarboxylic anhydride, naphthyl anhydride, naphthalene tetracarboxylic acid dianhydride, maleic anhydride, succinic anhydride, chlorendic anhydride, maleic acid, succinic acid, fumaric acid, oxalic acid, malonic acid, glutaric acid, adipic acid, dimer fatty acids, styrene/maleic anhydride polymers, and (meth)acrylic acid polymers and co-polymers.
In the case of compounds of formula (II), phosphorous containing compounds such as phosphorous pentoxide are used in place of the carboxylic anhydride compounds, and reacted with the unsaturated hydroxy compounds to form phosphate esters having acid functionality suitable for reaction with the metal salt.
In the case of compounds of formula (III), sulfur containing compounds such as sulfur trioxide are reacted with the unsaturated hydroxy compound to form sulfate esters which have acid functionality and later react with the metal compound. The compounds of formula (III) are novel.
Suitable metal compounds are those which can provide one or more metal (M) ions when reacted with the half esters prepared as described above. The suitable metals include lithium, sodium, potassium, cesium, magnesium, calcium, strontium, barium, titanium, zirconium, vanadium, chromium, molybdenum, tungsten, manganese, iron, cobalt, nickel, palladium, copper, zinc, cadmium, mercury, boron, aluminum, gallium, indium, silicon, germanium, tin, lead, antimony, bismuth, and the like. The metal compound can be, for example, the oxide, halide, alkoxide, hydroxide, nitrate, sulfate, carboxylate, and carbonate. The most preferred metal compound is zinc oxide since it reacts very easily, and is readily available.
The compounds of formulas (I), (II), and (III) can be prepared in an inert solvent, with very simple reaction conditions. For example, no catalyst is required. Water generated during the preparation can be removed by azeotropic distillation.
Suitable inert solvents include ethyl acetate, toluene, benzene, xylenes, hexane, heptane, and the like.
After preparation, the polymerizable unsaturated compounds are dissolved in an organic compound which is preferably also unsaturated, and is preferably copolymerizable with the compounds of formulas (I), (II), or (III). Some of such compounds are known in the art as reactive diluents.
The reactive diluents can be monomers or oligomers. Suitable reactive diluents include (meth)acrylic monomer, (meth)acrylic oligomer, vinyl monomer, vinyl oligomer, allyl monomer, allyl oligomer, propenyl monomer, propenyl oligomer, glycidyl ether, glycidyl ester, and the like.
Suitable (meth)acrylic monomers and oligomers include (meth)acrylate esters of C1-C20 alcohols, (meth)acrylate esters of ethoxylated or propoxylated C1-C20 alcohols, di(meth)acrylate esters of C2-C8 diols, di(meth)acrylate esters of ethoxylated or propoxylated C2-C8 diols, polyethylene glycol di(meth)acrylates, polypropylene glycol di(meth)acrylates, polyethylene/propylene glycol di(meth)acrylates, trimethyolpropane tri(meth)acrylate, ethoxylated or propoxylated trimethyolpropane tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ethoxylated or propoxylated pentaerythritol tetra(meth)acrylate, ethoxylated or propoxylated bisphenol-A di(meth)acrylate, bisphenol-A glycerolate di(meth)acrylate, C1-C20 alkyl glycidyl (meth)acrylates, aryl glycidyl (meth)acrylates, glycidyl (meth)acrylate, and the like.
Suitable vinyl monomers and oligomers include styrene, xcex1-methylstyrene, vinyl toluene, bromostyrenes, tert-butylstyrene, N-vinylpyrrolidone, N-vinylcaprolactam, N-vinylformamide, vinyl acetate, vinyl propionate, vinyl pivalate, vinyl stearate, vinyl 2-ethylhexanoate,methyl vinyl ketone, ethyl vinyl ketone, vinyl ethers of C1-C20 alcohols, 2,3-dihydrofuran, vinyl(meth)acrylate, allyl vinyl ether, and divinyl ether of C1-C20 diols, for example.
Suitable propargyl monomers and oligomers include dipropargyl ether, propargyl ethers of C1-C20 alcohols, propargyl (meth)acrylate, and the like.
After the reactive diluent is combined with the compound of formula (I), (II), and/or (III), the resultant solution can be stored without reacting, if desired, and then used to prepare the coatings, adhesives, and inks by conventional radiation cure techniques, for example, ultraviolet light (UV), or election beam radiation (EB), or microwave.
When the radiation is provided by UV, the composition should also include a photoinitiator. Such a photoinitiator is not necessary when EB is the source of radiation. Suitable photoinitiators for radiation curable compositions comprising a compound of formula (I), (II), or (III) and an ethylenically unsaturated comonomer or oligomer are those which promote free radical polymerization, generally of the unimolecular or bimolecular type. Examples of unimolecular type include isobutyl benzoin ether, benzil dimethoxy ketone, hydroxy aceto-phenone, acylphosphine oxide, and amino-alkylphenones. Examples of bimolecular type include benzophenone, derivatives of benzophenone, and combinations thereof with a hydrogen donating source.
For certain applications, it is not necessary or desirable to blend the compounds of formulas (I),(II), or (III) with reactive diluents. For other applications an inert solvent can be included in the compositions. In some cases, the compounds of formulas (I), (II), or (III) can be prepared in inert solvent and/or in the presence of copolymerizable ethylenically unsaturated monomer.
Hybrid cure polymerization of compositions comprising oil soluble polymerizable metal salts of formulas (I), (II), or (III), ethylenically unsaturated reactive diluent, and either epoxy resins or isocyanates can be carried out using a dual cure polymerization initiation system. In hybrid or dual cure systems, free radical polymerization of the polymerizable, metal salt with reactive diluent occurs simultaneously with, but independently of, a second type of polymerization, for example, a cationic initiated epoxy polymerization. Those skilled in the art will recognize other suitable polymerization reactions.
Cationic photoinitiators may also be used in the invention. Such cationic photoinitiators include diaryl ammonium salts and triaryl sulfonium salts. Examples of the cationic photoinitiators include diaryliodonium hexafluoroantimonate, triarylsulfonium hexafluoroantimonate, triarylsulfonium hexafluorophosphate, cyclopentadiene hexafluorophosphate, and the like.
Prior art formulations which employ oil insoluble metal salt crosslinking agents such as zinc diacrylate and zinc dimethacrylate can be modified and improved according to this invention by replacing the oil insoluble agents with a compound of formula (I), (II), and/or (III), with resultant great and surprising improvements in properties in many applications. The oil soluble metal salts can be used in combination with conventional insoluble metal salts such as zinc diacrylate.
Since the use of the insoluble salts in coatings or adhesives causes reduced gloss, whereas the compounds of the invention do not reduce gloss, combinations can be used to achieve controlled gloss. Use of the oil soluble metal salt compounds causes improved adhesion of the adhesives or coatings to substrates, improved abrasion resistance, heat resistance, clarity, tensile strength, modulus, interfacial adhesion, and toughness. Among the applications for which the coatings and adhesives are useful are can coatings, flooring coatings, pipe coatings, inks which have improved heat resistance, photoresists, coating metals where antimicrobial properties are desired, marine coatings, powder coatings, and the like. With powder coatings, the composition is solid at room temperature.
In the case of molded articles polymerized from solutions of the invention, very clear products can be obtained, with refractive index and transparency substantially matching that of glass, making the moldings useful for many applications, for example, lenses. In the case of lenses, the preferred refractive index is about 1.50 to 1.60. The preferred copolymerizable monomer is diallyl glycol carbonate.
Clear, transparent molded articles can be thermoset copolymers of a polyfunctional (meth)acrylate or allylic compound and a metal salt of formula (I), (II), (III), and can further include other monomers, for example, monofunctional (meth)acrylates, styrene, vinyl ethers, epoxys, and propenyl ethers.
The invention also encompasses compositions suitable as laminating resins. The laminating resins of the invention have a high heat distortion temperature. The laminating resin compositions of the invention include at least one compound of formula (I),(II), and/or (III) and at least one laminating resin. As used herein, xe2x80x9claminating resinsxe2x80x9d are unsaturated polyester resins based on maleic anhydride. These are made from maleic anhydride, glycols (such as propylene glycol, ethylene glycol, diethylene glycol, and the like), and dicarboxylic acids (such as adipic acid, orthophthalic acid, isophthalic acid, and the like).
The invention includes a process for coating a substrate with the composition. Suitable substrates may be of any type. A preferred substrate is metal. In the process, a substrate is coated with a composition comprising at least one compound of the formula (I), (II), or (III), and at least one ethylenically unsaturated monomer or oligomer, and is subsequently irradiated. The process may also include exposing the coating composition to heat. The cured coating compositions are able to withstand pasteurization and retort conditions substantially without degradation of the cured coating.
Coating compositions may also be formed of at least one compound of the formula (I), (II), or (III), and a fatty acid-modified alkyd resin. The amount of the compound of formula (I), (II), or (III) should be sufficient to improve the adhesion of the coating to the substrate to be coated. In curing the coating composition containing the fatty acid-modified resin, a free radical initiator may be added along with a metal salt drying agent in an amount effective to aid in the decomposition of the free radical initiator. The invention also embraces the method of coating a substrate with the coating composition containing the fatty acid-modified alkyd resin and curing the coating composition.
The fatty acid-modified alkyd resins suitable for use in the invention include polyester resins based on polyhydroxy compounds with carboxylic anhydride and a fatty acid. These compounds may be used with free radical initiators such as organic peroxides. Examples of suitable organic peroxides include cumene hydroperoxide, methylethyl ketone peroxide, and the like.
The metal salt drying agents which may be used in this embodiment of the invention include a cobalt naphthanate, cobalt octoate, and the like.
Various additives which are well known may be incorporated in the polymerizable solutions. Although the oil insoluble polymerizable metal salts of the prior art should not be incorporated for most applications of the invention, they may be added to obtain certain effects, for example when low gloss is desired.
The following non-limiting examples illustrate a few embodiments of the invention.